Study On Control Module And Communication Of Intelligent Control And Protective Swithing Devices

The control and protection of electric motor need the thermal relay, contactor, circuit breaker and other low voltage electrical apparatus in traditional electric control system, which is unsatisfactory in the occupation of space, reliability and convenience. Control and protective switching devices set the functions of low-voltage electrical appliances above as a whole. It has been widely researched cause the advantages of small volume and good matching performance. At present, control and protective switching devices has the defect of phase randomized and high power consumption, therefore the research on intelligent control technology is very necessary.Firstly, the intelligent control technology of the control and protective switching devices was researched, which includes phase selection, energy saving and zero current breaking technologies. The intelligent control method of switching relay was studied in detail. By using three electronic power switches which separately control the AC circuit, DC circuit and relay, the moment of high power switching was avoid.Secondly, the control module was designed through analysis in detail. It could be divided into hardware circuit and software design. The hardware circuit includes power circuit, zero crossing detection circuit, signal acquisition circuit, control circuit, communication circuit, display circuit and keyboard circuit. The output signals were measured after design.Thirdly, communication between PC and microchip was developed by application of RS485 bus, MODBUS communication protocol after labor.Finally, properties tests were done to verify the design requirements. The tests of control module properties include power consumption and temperature rise, dynamic characteristic, the voltage and current acquisition function and switching performance. The results confirmed that the control module works well.